Anyway, much of the content of the press briefing consisted of updates or refinements to the discoveries announced shortly after the flyby in January -- there's a dipolar magnetic field and not much in the way of small-scale magnetic field structure, both of which indicate that Mercury's core is still partially molten and generating the field via a dynamo, just like Earth's; there's lots of stuff in the MESSENGER images that looks like volcanic constructs, settling a 30-year-old-debate; there's interesting stuff to be seen in the composition of the neutral species in Mercury's extended atmosphere. The biggest and newest news this week came out of the FIPS instrument (the Fast Imaging Plasma Spectrometer), which found water -- water?!? -- in Mercury's exosphere, and quite a lot of it. Go read my news article for the rest of the story.